1. Field of the Invention
This invention relates to a method of preparing 4-amino-3,5,6-trichloropicolinic acid, in a one step process of aminating and hydrolyzing 3,4,5,6-tetrachloropicolinonitrile.
2. Description of Prior Art
It is known that 4-amino-3,5,6-trichloropicolinic acid is prepared by a two-step method where heptachloro-2-picoline is aminated with anhydrous liquid ammonia to form 4-amino-hexachloro-2-picoline, an intermediate product that is isolated, and which is in turn hydrolyzed with sulfuric acid to form 4-amino-3,5,6-trichloropicolinic acid. See, for example, Russian Pat. No. 445,662.
Russian Pat. No. 445,662 also teaches a method of producing 4-amino-3,5,6-trichloropicolinic acid by treating heptachloro-2-picoline with aqueous ammonia at a temperature of from 120.degree.-180.degree. C. resulting in the formation of the ammonium salt of 4-amino-3,5,6-trichloropicolinic acid which is then acidified to obtain the free acid.
It is also suggested by Morrison and Boyd, Organic Chemistry, 3rd Ed., New York University, 1973, p. 586, that aromatic nitriles may be hydrolyzed with an acid or a base to form the corresponding carboxylic acid.